Forming characteristics and mechanism of double-roll rotary forging for large-diameter and thin-walled metal discs

Abstract

Double-roll rotary forging is an emerging plastic forming technology based on rotary forging. Owing to the advantages of labor saving, small eccentric load, low noise and vibration, good uniformity, high surface quality and material saving, it is very promising for fabrication of large-diameter thin-walled disc. To date, few relevant research on the double-roll rotary forging technology of large-diameter thin-walled metal discs has been reported, and the forming mechanisms and process of disc workpieces remains uninvestigated. Herein, a 3D rigid-plastic finite element model (FEM) is established to simulate the fabrication process of large-diameter thin-walled disc, four geometric features appear in the forming process: "mushroom" shape, "upper drum" shape, "drum shape" shape and "lower drum" shape. Equivalent stress, equivalent strain and temperature field of these four geometric shapes are analyzed, and the forming mechanism of these four geometric shapes is revealed. The reliability and accuracy of FEM are verified through experiments and the four geometric shape features occur in the process are consistent with the simulation. The research results provide valuable guidelines for better understanding of double-roll rotary forging for the fabrication of large-diameter thin-walled discs.